JP2516638B2 - Accident position detection method for electric current path - Google Patents

Description

The present invention relates to a method for detecting a fault position in a current path, mainly using a Faraday element connected in series by a single mode optical fiber.

"Prior Art" Conventionally, an optical magnetic field sensor using a Faraday element has been applied to current measurement to detect a short circuit accident in a current path including an accident position. There is a method shown in FIG.

The means shown in FIG. ₂ are the optical magnetic field sensors S ₁ and S ₂ attached to the measuring parts P ₁ and P ₂ on the current path (power cable) E _c , the electric / optical converter E / O and the optical / electrical converter E / O. Electrical converter O / E and these optical magnetic field sensors S ₁ , S ₂ , electrical / optical converter E / O, optical / electrical converter O
It is composed of optical fibers F ₁ and F ₂ that connect / E to each other and phase shift determination units D ₁ and D ₂ .

In the means of FIG. 2, when a short circuit accident occurs in the current path E _c , the following is done.

For example, if a short-circuit accident occurs between the measurement parts P ₁ and P _{2 of} the current path E _c , the alternating currents flow in opposite directions on the positions P ₁ and P ₂ and have opposite phases. If the Faraday rotation angles of S ₁ and S ₂ are in opposite phases and a short-circuit accident occurs outside the measuring parts P ₁ and P ₂ , the alternating current is directed in the same direction on the measuring parts P ₁ and P _2. Since they flow in the same phase, the optical magnetic field sensor
The Faraday rotation angles of S ₁ and S ₂ are in phase.

Therefore, when an accident occurs in the current path E _c, the comparison of the phase, or the accident position is between P _1, P _2, it can be determined whether the outside between the P _1, P ₂ is.

The means shown in FIG. 3 is based on the principle of FIG. 2 described above, and the optical magnetic field sensors S ₁ , S ₂ are arranged in accordance with the measurement parts P ₁ , P ₂ , P ₃ (at least three points) of the current path E _c. , S ₃ ... are provided, but in this case as well, the accident position of the current path E _c can be determined by comparing the phases of the adjacent measuring parts P ₁ , P ₂ , P ₃ .... Prove.

[Problems to be Solved by the Invention] In the case of the above-mentioned conventional technique, the measuring points (measuring points P ₁ , P ₂ , P ₃
......) Each requires an electrical / optical converter, an optical / electrical converter, a phase determination device, a signal transmission line, etc. As a result, a long section such as a current line is divided into many measurement points. With this setting, the equipment for detecting the accident position becomes complicated and large-scale, and the total economic burden including each component, individual assembly labor, etc. increases, so maintenance of the current path,
Not easy to check.

The present invention, in order to solve the problems of the conventional example described above,
It is an object of the present invention to provide a method capable of detecting a short circuit accident position in a current path by a simple and economical means.

[Means for Solving Problems] A method for detecting a fault position in a current path according to the present invention is a method for setting a plurality of measurement units in a current path at intervals in a length direction and a single mode transmission type optical fiber. A plurality of Faraday elements connected in series via the above are arranged along the current path corresponding to each measurement section of the current path, and a short circuit accident occurs between any of the measurement sections in the current path. When it occurs, the total Faraday rotation angle of each Faraday element obtained by passing the polarized light through all Faraday elements is compared with the Faraday rotation angles of the reference Faraday elements at both ends of the current path, and the accident The object of the invention is achieved by detecting the measurement unit that has caused.

[Example] An example of the method of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a current path having a plurality of measuring parts P ₁ , P ₂ , P ₃ divided in the length direction.

10, 11, 12 are analyzers, 20, 21, 30, 40, 42 are Faraday elements, 50, 51, 52 are polarizers, 60, 61, 62 are light emitting parts, 7
Reference numerals 0, 71, and 72 are light receiving portions.

Reference numeral 80 is a judgment device having an electronic or electric comparison calculation function.

90, 91, and 92 are single-mode transmission type optical fibers.

In FIG. 1, the plurality of Faraday elements 20, 30, 40 are
While connected in series via the optical fiber 90,
It is arranged along the current path 1 corresponding to each of the measuring parts P ₁ , P ₂ and P ₃ .

A polarizer 50 is interposed between the Faraday element 40 and the light emitting unit 60, and the Faraday element 40, the polarizer 50, and the polarizer 50 are interposed.
The light emitting section 60 and the light emitting section 60 are connected to each other via an optical fiber 90.

Between the Faraday element 20 and the light receiving section 70, an analyzer 10 in which an optical bias of 45 ° is set with respect to the polarization axis of the polarizer 50 is interposed, and the Faraday element 20 and the analyzer 10,
The analyzer 10 and the light receiving section 70 are connected to each other via an optical fiber 90.

Thus, an optical transmission system from the light emitting unit 60 to the light receiving unit 70 is configured.

In the measurement section P ₁ located at one end of the current path 1, an optical bias of 45 ° was set between the Faraday element 21 and the light receiving section 71 which are arranged adjacent to the Faraday element 20. An analyzer 11 is interposed, and a polarizer 51 is interposed between the Faraday element 21 and the light emitting section 61, and the Faraday element 21 and the analyzer 11, the analyzer 11 and the light receiving section 71, and the Faraday element 21. The polarizer 51, the polarizer 51, and the light emitting unit 61 are connected to each other via the optical fiber 91, thus forming an optical transmission system from the light emitting unit 61 to the light receiving unit 71.

In the measurement section P ₃ located at the other end of the current path 1, an optical bias of 45 ° is set between the Faraday element 42 and the light receiving section 72, which are arranged adjacent to the Faraday element 40. The analyzer 12 is interposed, and the Faraday element 42 and the light emitting section 62 are provided with a polarizer 52. The Faraday element 42 and the analyzer 12, the analyzer 12 and the light receiving section 72, and the Faraday element 42. And the polarizer 52, and the polarizer 52 and the light emitting section 62 are connected to each other via the optical fiber 92, thus forming an optical transmission system from the light emitting section 62 to the light receiving section 72.

Each of the above-described light receiving units 70, 71, 72 is connected to the determiner 80.

In the embodiment of FIG. 1, for example, if the short circuit between the measuring unit P _1, P ₂ is generated, the short circuit I ₁ flows in the measuring unit P _1, the measuring unit P _2, the P ₃ short-circuit current I ₂ flows, and as a result, the Faraday rotation angle θ ₁ proportional to the short-circuit accident I ₁ is applied to the Faraday elements 20 and 21, and the Faraday rotation angle θ ₂ proportional to the short-circuit current I ₂ is applied to the Faraday elements 30, 40 and 42. Occurs respectively.

At this time, each single mode transmission type optical fiber 90, 9
Polarized light transmitting 1 and 92 are analyzed by analyzers 10, 11, and 12, respectively.
Since the intensity is modulated by, the output change of each of the light receiving units 70, 71, 72 is proportional to θ = θ ₁ + 2θ ₂ , θ ₁ , θ ₂ .

Here, the determiner 80 performs a comparison calculation of θ−3θ ₂ and θ ₁ −θ ₂ as in the formula.

Determiner by 80 θ-3θ _2: When the ratio of theta ₁ - [theta] ₂ is 1, which means that short-circuit accident current path 1 occurs between the measuring unit P _1, P _2.

Similarly, when a short circuit accident occurs between the measurement parts P ₂ and P ₃ of the current path 1, the output changes of the light receiving parts 70, 71 and 72 are θ = 2θ ₁ + θ ₂ , θ ₁ and θ ₂ , respectively. It becomes proportional, and the determiner 80 performs the comparison operation of the equation.

When the ratio is 2 as in the above equation, it means that a short circuit accident of the current path 1 has occurred between the measuring members P ₂ and P ₃ .

Generally, in the case of a short circuit in the current path, | θ ₁ | ≠ | θ ₂ |.

Even if | θ ₁ | = | θ ₂ |, since the polarities of θ ₁ and θ ₂ are opposite, θ ₁ −θ ₂ ≠ 0, and this determination method is always effective.

When a short-circuit accident in the current path 1 occurs outside the measuring parts P _{1 to} P ₃ , θ ₁ = θ ₂ , so that the measuring part P ₁ to
It turns out to be a short circuit accident outside P ₃ .

In addition, if there are a large number of measuring parts of the current path 1 such as P ₁ , P ₂ ... P _N , it becomes as follows.

That is, θ in the current path 1 is given by the equation.

In the current path 1, for example, when a short circuit accident occurs between the measurement units P _i and P _{i + 1} , θ is given by the formula.

θ = i · θ ₁ + (N−i) θ _N …… By calculating the above formula based on the formula (judgment device), a short circuit accident has occurred between the measuring parts P _i and P _{i + 1.} Turns out.

As described above, in the current path fault position detection method according to the present invention, it is possible to deal with an arbitrary number of measurement units by slightly changing the configuration of the determination device used for this, and furthermore, the optical fiber is used. As a result, the accident position can be detected over a long-distance (long current path) measurement section.

[Effects of the Invention] As described above, according to the method of the present invention, when the sum of the Faraday rotation angles of each Faraday element is compared with the Faraday rotation angle of the reference Faraday element to detect the accident position of the current path. It is not necessary to equip each measuring part of the current path with an electrical / optical converter, an optical / electrical converter, a phase determination device, a signal transmission path, etc. Therefore, the equipment for detecting the fault position of the current path is simple. It will also be economical and the maintenance and inspection of the current path will be easy.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the method of the present invention, and FIG.
FIG. 3 and FIG. 3 are explanatory views schematically showing the conventional method. 1 ... current path 10, 11, 12 ... analyzer 20, 21, 30, 40, 42 ... Faraday element 90, 91, 92 ... optical fiber 51, 52, 53 ... polarizer 61, 62, 63 ...... Light emitting part 71, 72, 73 …… Light receiving part 80 …… Judger 61, 62, 63 …… Light emitting part P _{1 to} P ₃ …… Measuring part

Claims (1)

(57) [Claims] 1. A plurality of measuring units are set in the current path at intervals in the length direction, and a plurality of Faraday elements connected in series via a single mode transmission type optical fiber are connected to the current path. It is placed along the current path corresponding to each measurement section, and when a short circuit accident occurs between any of the measurement sections in the current path, polarized light can be obtained by passing through all Faraday elements. Compare the sum of the Faraday rotation angles of each Faraday element and the Faraday rotation angles of the reference Faraday elements at both ends of the current path,
A method for detecting an accident position in a current path, which is characterized by detecting a measuring unit that has caused an accident.